PEX and Shark BIte fittings for LP air?

Active Member

I want to run an air line in my basement, but I don't want the (noisy) compressor down there. The idea is to run a line to an external chuck and charge the system from the compressor in my garage.

I know PEX tubing is rated for air, and I'd really love to use shark bite fittings for the ends. They are not specifically rated for air or gases, but this would be regulated to a max of 50 psig, more likely 25. It's for airbrushing and a mist-coolant system for my lathe and mill.

H-M Supporter - Commercial Member

I realize that you are planning on running at lower than rated pressure. But even that is has potential for catastrophe when someone other than you decides to take control of the system. I am sorry, I am not a fan of pressurized plastic pipe. Plastic gets brittle over time and when it lets loose, it blast shrapnel everywhere. Just a warning, you do what you have to do.

Mechanical Hacker

PEX is fine and so are shark bites, but shark bites are expensive. When I plumbed my shop for air I used high pressure (rated 150 psi) polyethylene tubing and plastic compression fittings (220 psi) from McMaster. The tubing is about 1/3 the cost of PEX and the fittings are a lot cheaper than shark bites. 5 years later it's still holding up fine.

H-M Supporter - Gold Member

One concern in using plastic for compressed air is what happens if the system ruptures. Unlike water under pressure, compressed gas expands as it depressurizes. Loose lines can whip around with possible serious consequences.

Newbie

One concern in using plastic for compressed air is what happens if the system ruptures. Unlike water under pressure, compressed gas expands as it depressurizes. Loose lines can whip around with possible serious consequences.

That’s why you strap/clip the supply line down every so often, every couple feet would be or should be sufficient in most applications.

That’s also why I’d prefer using a metal compression type fitting over a plastic sleeved one....even in the gulf on boat landing pull stations we install nylon ferrules in the compression fittings and one can pull the poly flow line out of the fitting when jerked hard to esd the facility.....matter fact BSEE the gov regulator and inspectors look for that they don’t have metal ferrules because it just won’t pull through....

Plastic will compress then up n greater forces slide against plastic but will be bitten into by a metal ferrule until enough if possible force applied to actually stretch the tubing

I’m a Sr. Pneumatic Instrumentation And slow speed motor controls specialist in oil and gas facilities in the g.o.m.

Active Member

After considering pressures and volumes required and pricing everything out, I decided to go with 3/8 polyethylene tubing and plastic PEX fittings.

100 feet of tubing, all the fittings, clamps to tack the tubing to the beams, and two water separators - enough to do two drops in the basement, one by the machines, one in the hobby room for the airbrush - came to just under $100.

I did decide to add an additional regulator to the drop in the hobby room as I may need to adjust pressures for the airbrush and it'll save running up to the mudroom every time. Need to get some pieces-parts for that.

Active Member

For general use, I'd certainly agree with you. However, this line will only run a mister nozzle and perhaps an airbrush, so volume really isn't an issue. Also I plan to regulate the line to 50 psi max and more likely run it at 25 psi.

H-M Supporter - Sustaining Member

You could run the supply line to a storage cylinder in the shop and then distribute from there, that way you will limit the sudden pressure drop when you use air. A long supply line at 3/8 will drop supply pressure quite quickly with only a small demand, but storage cylinder will help prevent it being a problem.